Recently, in a field of biochemical test or genetic test, high detection sensitivity for a measurement object has been required, and positioning of a fluorescent dye as a labeling agent (a labeling substance) has become an important factor.
As the fluorescent dye, there have been used, for example, a cyanine dye derivative, a coumarin dye derivative, a fluorescein dye derivative, a rhodamine dye derivative and the like, depending on various objectives, and among these, the cyanine dye derivative has been widely used as a dye having fluorescence characteristics in a near-infrared region of equal to or higher than 600 nm.
As the cyanine dye derivative, for example, Cy3, Cy5 [manufactured by GE Healthcare Bioscience Co., Ltd. (former name: Amasham Bioscience Co., Ltd.)] or the like are known as a leading fluorescent reagent, and it is a present situation that also as a photometric specification of an detection apparatus, fluorescence characteristics of Cy5 is used as a basis.
Under these circumstances, development of the cyanine dye derivative has been continued, using two wavelengths of Cy3 and Cy5 as bases of excitation wavelength. Cy3 and Cy5 have a structure (an indolenine-based cyanine dye) where two indolenine skeletons are bound to a polymethine chain, and by using this structure as a basic structure, various cyanine dye derivatives have been developed aiming at, for example, improvement of water-solubility, higher sensitivity by avoiding an aggregation state or the like (see Patent Document 1, Patent Document 2, Patent Document 3 or the like).
In addition, as other cyanine dye derivatives, there have been developed those having a structure where an azaindolenine skeleton and a pyrazole skeleton are bound to a polymethine chain (see Patent Document 4, Patent Document 5 or the like).
Still more, there have been developed those having a structure where two indolenine skeletons bound to, for example, a polymethine chain or the like are further cross-linked with a spacer or the like (see Patent Document 6, Patent Document 7, Patent Document 8 or the like).
On the other hand, a laser light source used in an optical system has been made to have increasingly shorter wavelength, and higher output, in order to attain larger capacity of a magnetic optical disk. In addition, also a semiconductor laser or the like, having very small and stable temperature drift width, has become available.
Under these circumstances, there has been desired development of a novel cyanine dye derivative having fluorescent characteristics with higher sensitivity than a conventional dye, in an energetically more efficient short wavelength region than conventional optical characteristics.    Patent Document 1: U.S. Pat. No. 5,268,486    Patent Document 2: U.S. Pat. No. 5,486,616    Patent Document 3: U.S. Pat. No. 5,569,766    Patent Document 4: JP-A-2003-034696    Patent Document 5: JP-A-2003-034697    Patent Document 6: U.S. Pat. No. 5,571,388    Patent Document 7: U.S. Pat. No. 5,800,995    Patent Document 8: WO01/02374